Despite its name, Earth is perhaps the only planet in our solar system that has oceans. It is the fifth largest planet in the solar system and perhaps the only one to hide life. The Earth's seas and oceans, which cover 70% of its surface, are home to a great deal of life. With an average depth of 4 km, they represent 97% of the planet's water. In addition, they have some impressive landforms: the longest mountain range, the Mid-Ocean Reef, is right at the bottom of the sea. Four times longer than the Andes, the Rocky Mountains and the Himalayas lined up in a row, it stretches 65,000 km across the Arctic and Atlantic. A study carried out jointly by the universities of Münster, Cambridge and Zurich Technique found that the age of the planets is between 4400 and 4.510 million years. So far, five mass extinctions have been recorded on the planet. The first occurred 440 million years ago and the last 65 million years ago. Michael Rampino, an Earth science expert at New York University, says it takes about 30 million years for the solar system to cross the plane of the Milky Way. The presence of the system may be one of the reasons why the comets' orbits destabilize, throwing them towards the planet. To that he adds a possibility little studied today: dark matter. 8.7 million species, one planet. The ecosystems we depend on as humans to survive consist of about 8.7 million plant and animal species. This is at least confirmed by a study carried out by the University of Hawaii (United States) in 2011, which is considered the most accurate to date. We only know 1.3 million of them. Unfortunately, the WWF warns with its Living Planet report that since the 1970s, the world's vertebrate population alone has declined by 60% due to global warming, ecosystem destruction and man-made biodiversity crisis. It is in our power to care for and protect (and even discover) all the species that make our planet an (almost) inexhaustible source of life.